﻿//https://leetcode.cn/problems/add-two-numbers/?envType=study-plan-v2&envId=top-100-liked

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* cur1 = l1, * cur2 = l2;
        ListNode* newhead = new ListNode(0);
        ListNode* tail = newhead;
        int carry = 0;
        while (cur1 || cur2 || carry)
        {
            if (cur1)
            {
                carry += cur1->val;
                cur1 = cur1->next;
            }
            if (cur2)
            {
                carry += cur2->val;
                cur2 = cur2->next;
            }

            tail->next = new ListNode(carry % 10);
            tail = tail->next;
            carry /= 10;

        }
        tail = newhead->next;
        delete newhead;

        return tail;

    }
};